Unable to create surface with bsurface addon
Set Bezier spline type for your curves.

As the warning is saying, you need to work with "bezier" spline type. They are currently "poly" type (probably because you created the curves from mesh conversion, and by default poly is the choosen type).

Select all the curves and click the button you can find in the tool shelf under the Curve Tools section. A menu will pop up letting you choose the spline type for the selected curves.